Contact lenses from a wide range of materials are nowadays produced in great volumes in highly automated manufacturing lines. To ensure top quality of the manufactured contact lenses, the final contact lenses are optically inspected prior to packaging. Because contact lenses are intended for use on the eye, great care must be taken to make sure that the lenses meet strict quality standards.
In order to ensure the quality of the contact lenses, they are transferred into an inspection system which evaluates if the considered contact lens meets the strict requirements according to set parameters. For reasons of simplifying the evaluation of the parameters, the criteria generally are set for a contact lens which is properly oriented on the lens holder. A lens holder may, for example, be a bottom of an inspection cuvette. A properly oriented contact lens means that the contact lens is oriented in such a manner on the lens holder, that the curved surface of the contact lens is oriented towards the surface of the lens holder bearing the contact lens during the inspection step. In case of a properly oriented contact lens, the lens edge is oriented upwards in the opposite direction away from the bearing surface of the lens holder. In case the contact lens is oriented upside-down, the lens edge is oriented towards the bearing surface of the lens holder. In case the contact lens is not properly oriented on the bearing surface of the lens holder (upside-down orientation), the evaluation of the considered contact lens whether or not the contact lens meets the strict quality requirements cannot simply be performed using set parameter values. Additionally, detecting an upside-down oriented contact lens may trigger additional measures in the subsequent steps, such as reorienting the contact lens.
Accordingly, there is a need for a reliable inspection method and system which detects whether the contact lens is properly oriented on the lens holder. A contact lens inspection method and system shall be provided, which is relatively simple, and which provides accurate results in particular with regard to the detection of upside-down oriented contact lenses. The contact lens inspection method and system shall be in particular capable of being combined with and integrated into an automated manufacturing line for contact lenses.